972 
Journal of Agricultural Research 
Vol. XXVIII, No. 9 
Fertilizer 
Composition (per 
cent) 
N 
P 2 O 5 
Ammonium sulphate___ 
21.02 
16.16 
12. 55 
45. 70 
33. 93 
5. 38 
20.27 
6. 30 
33.23 
66. 43 
Sodium nitrate.... 
C alcium nitrate___ 
Urea........ 
Ammonium nitrate. _____ .. 
Ammoniated superphosphate____ 
a 14. 66 
Cyanamid (unhydrated and unoiled) ____ 
Urephos______ 
b 3. 66 
Guanylurea sulphate........ 
Dicynnodiamide._______ .. . 
Acid phosphate. ........ 
e 16.12 
d 17. 53 
Calcined phosphate...... 
° Solubility in 2 per cent citric acid; total, P 2 O 5 —17.45 per cent. 
b Solubility in 2 per cent citric acid; total, P 2 O 5 —6.36 per cent, 
c Solubility in ammonium citrate; total, P 2 O 5 —17.50 per cent. 
d Solubility in 2 per cent citric acid; total, P 2 O 5 —27.16 per cent. 
SOIL PREPARATION AND FERTILIZATION 
The sieved moist soils were weighed out into portions equivalent to 10 pounds 
of air-dried soil and the fertilizers thoroughly mixed with each portion. Two 
pots were used in each treatment. When the young plants were about a week 
old, they were thinned to 5 and 3 plants per pot, respectively, for the wheat and 
beans in “the first experiment, and 10 plants per pot for the wheat in the second 
experiment. The general plan of the experiment is apparent from Tables I and II. 
The quantities of fertilizers used were based on field applications, assuming 
2,000,000 pounds of soil per acre to a depth of 6 inches. All pots, except those 
designated as “no fertilizer,” received 80 pounds of P 2 0 5 and 40 pounds of K 2 0 
per acre in the forms of acid phosphate and potassium sulphate, respectively, 
except where otherwise noted. Ammonia was added at the rates of 10, 40, 80, 
and 160 pounds per acre. Where acid phosphate was used with cyanamid, the 
materials were applied separately. In some instances, calcined phosphate was 
used in admixture with cyanamid and also in one ammonium sulphate series for 
comparison. In the cases of urephos and ammoniated superphosphate (in the 
lowest application) acid phosphate was used to bring the P 2 0 5 content up to 
the proper amount. With the medium and heavy applications of ammoniated 
superphosphate, however, the P 2 0 5 contained in the material itself was in excess 
of the application decided upon. The nitrogenous materials were applied at 
various rates depending upon the material used. Adequate control pots were 
included in which applications of phosphate and potash were made, but no 
nitrogen. 
EXPERIMENTAL RESULTS 
AVAILABILITY STUDIES WITH BEANS AND WHEAT 
The bean and wheat plants were harvested at the end of five and eight weeks, 
respectively. The relative green weights of the plants grown on the two soils 
with the different sources of nitrogen are summarized in Table I. 
An examination of the table shows that ammonium sulphate, ammonium ni¬ 
trate, ammoniated superphosphate, cyanamid, and urea all gave good increases 
in yields over the no-nitrogen fertilizer pots. The relative values of the different 
nitrogen carriers varied at the different rates of application and also varied 
with the soil and crop grown, as might be expected. The variations between the 
results obtained with the fertilizers used under a given set of conditions were, 
